Key cylinder lock sets are well known and commonly used in many applications, including, for example, padlocks, residential and commercial entry doors, and vehicle door applications. It is often desirable to change or “re-key” a lock to prevent access to a locked structure or enclosure by the holder of an authorized key, for example, when a key is lost or stolen, or when access (such as by a former employee or resident) is no longer necessary or desirable. While re-keying some key cylinder locks requires disassembly of the lock and removal of the cylinder plug from the cylinder body to replace or rearrange tumblers, other key cylinder lock sets have been developed to include recoding or re-keying mechanisms that allow a user to alter the locking mechanism to accept a different authorized key. For example, a recodeable key cylinder lock arrangement may be configured such that, upon insertion of an authorized key and selective movement of the locking mechanism to a recoding condition (such as by rotation of the key to a recoding orientation and/or insertion of a tool into the lock cylinder), insertion of a different key may cause the locking mechanism to become configured to be unlocked by the different key.
In one embodiment, a recodeable key cylinder lock may include a sidebar configured to be movable from a locked condition to an unlocked condition to disengage a locking portion of the sidebar from a corresponding locking portion of the housing for rotation of the cylinder plug. Insertion of an authorized key moves a series of wafer tumblers to unlocking positions, in which code blocks (disposed in corresponding unlocking positions) assembled with the sidebar engage notches in the wafer tumblers to allow the sidebar to move to the unlocked condition. Rotation of the cylinder plug to a recoding orientation allows a liftbar to engage an appendage of a codebar for release of the code blocks from the sidebar, such that the code blocks may be moved to new unlocking positions corresponding to a coded surface of a new authorized key.
One such exemplary embodiment of a key cylinder lock set configured to allow for this type of recoding operation is described in U.S. patent application Ser. No. 11/244,881 (Publication No. 2006/0117822) (the “'881 application”), entitled LOCK APPARATUS AND METHOD, the entire disclosure of which is incorporated herein by reference, to the extent that it is not conflicting with the present application. In the exemplary embodiment (illustrated in FIGS. 36A-36I of the '881 application, and corresponding FIGS. 1A-1I herein), a recodeable lock 929 includes a cylinder plug 930 configured to receive an authorized key 901 (FIG. 1A) for engaging a series of slidable wafer tumblers 923 (FIGS. 1B, 1C, and 1I) to align notches 935 disposed on the wafer tumblers 923 with corresponding protrusions 910 (FIG. 1G) associated with a sidebar 984 (FIGS. 1B and 1C). Upon alignment of the notches 935 and protrusions 910, the sidebar 984 becomes movable (by flexible arm 976 on sleeve 920) to disengage from a notch 916 (FIG. 1B) of the housing 914, thereby allowing the cylinder plug 930 to be rotated to an unlocked orientation. The protrusions 910 are disposed on a series of code blocks 908 (FIGS. 1B and 1G-1I) positioned in channels 983 of the sidebar 984 and are each secured at a fixed distance from the key axis by serrations 909 on the code blocks 908 that interlock with corresponding serrations 951 on posts 950 of a codebar 946 (FIGS. 1D and 1G) that is received in apertures 977 of the sidebar 984 (FIG. 1C).
To modify or “recode” the locking mechanism to accept a different key for unlocking the lock, an authorized key is inserted into the key cylinder plug 930 to align the wafer notches 935 with the code block protrusions 910 to allow the sidebar 984 to disengage the notch 916 in the cylinder housing 914 to permit rotation of the plug 930 and sidebar 984 about the key axis (by turning the key). When the cylinder plug 930 and sidebar 984 are rotated to a recoding orientation (FIG. 1D), an appendage 945 of the codebar 946 engages a catch 995 of a liftbar 985. A tool 905 may then be inserted into an access hole 919 of the housing 914 to move a pivot lever 991 engaged with the liftbar 985 (FIG. 1E), such that the liftbar 985 moves the codebar posts 950 out of engagement with the code blocks 908, allowing the code blocks 908 to move radially with respect to the key axis (along channels 983 in the sidebar 984). Upon insertion of a new key (which the user intends to use as the new authorized key), the coded surface of the new key moves each of the code blocks 908 (which are still engaged with corresponding wafer tumblers 923) against corresponding springs 924. Subsequent withdrawal of the tool 905 allows a biasing member 966 to return the codebar posts 950 to engagement with the code blocks 908, thereby securing the code blocks 908 in new radial positions with respect to the key axis. Consequently, the new positions correspond to the coded surface of the new key. Thereafter, insertion of the new key in the cylinder plug 930 aligns the wafer notches 935 with the code block protrusions 910 for disengagement of the sidebar 984 from the housing notch 916 and rotation of the cylinder plug 930 to either of the unlocked and recoding orientations. Also, to ensure that the key is fully inserted in the lock when recoding, an anti-rotation block 980 (FIGS. 1B and 1C) is provided in the cylinder plug 930 for interlocking engagement with the cylinder housing 914, with the anti-rotation block 980 being configured to disengage from the housing 914 upon full insertion of the key. The anti-rotation block 980 includes a flex arm 981 that biases the block 980 back to interlocking engagement with the housing 914 upon withdrawal of the key.
In the illustrated embodiment of the '881 application, the liftbar 985 and pivot lever 991 are disposed in a holding block 917 (FIGS. 1D and 1E) extending from an outer cylindrical surface of the housing 914 (and may, but need not, be integral with the housing 914). A spring cover 921, from which the biasing member 966 extends, is secured to the holding block 917 to retain the liftbar 985 and pivot lever 991. To allow for engagement of the codebar appendage 945 with the liftbar catch 995, a slot or channel 913 is provided in the housing 914 (FIG. 1B), through which the codebar appendage 945 may travel as the cylinder plug 930 and sidebar 984 are rotated between locked, unlocked, and recoding orientations. A notch in the holding block 917 (FIG. 1B) permits the appendage 945 to enter the holding block for engagement with the liftbar catch 995 in the recoding orientation. However, as the channel 913 is unable to extend around the entire circumference of the housing 914, travel of the codebar appendage 945 and rotation of the cylinder plug 930 and sidebar 984 is limited to less than 180.degree.. This limitation may restrict the applications in which the recodeable key cylinder lock set may be used, as some applications require upwards of 360.degree. rotation of the key cylinder plug to operate the latch with which the key cylinder is being used.